ANALYSIS OF SMALL SIGNAL CHARACTERISTICS IN POWER SYSTEMS INCORPORATING WIND ENERGY AND ENERGY STORAGE UNITS

Abstract

This paper presents a comprehensive study of the small signal behavior of power
systems, incorporating both wind generation units and energy capacitor systems (ECSs). The
modeling of wind units, which feature squirrel-cage induction generators connected to the power
system via a full-scale AC/AC converter, as well as the ECS unit, is elaborated upon in detail.
The ECS unit, as considered in this study, is comprised of electric double-layer capacitors
(EDLC) and a DC/AC converter. Through digital computer simulations, the small signal
behavior of three test systems is thoroughly investigated and compared. These systems include:
System S1: The WSCC 9-bus system equipped with three conventional synchronous generators
(SGs). System S2: The WSCC system with one of the conventional SGs replaced by a wind
energy system. System S3: Similar to S2, but with the addition of an ECS unit. The study
encompasses a comparison of dominant eigenvalues, participant state variables, and related
participation factors for each of the three systems. Furthermore, the paper delves into analyzing
the effects of loading on the unstable modes of System S3, which incorporates conventional SGs,
wind generation units, and ECS units, by examining the trajectory of these modes as loads are
incrementally increased.